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PDF MAX8521 Data sheet ( Hoja de datos )
| Número de pieza | MAX8521 | |
| Descripción | Smallest TEC Power Drivers | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-2586; Rev 1; 12/08
EVAALVUAAILTAIOBNLEKIT
www.DataSheet4U.com
Smallest TEC Power Drivers for Optical
Modules
General Description
The MAX8520/MAX8521 are designed to drive thermo-
electric coolers (TECs) in space-constrained optical
modules. Both devices deliver ±1.5A output current
and control the TEC current to eliminate harmful current
surges. On-chip FETs minimize external components
and high switching frequency reduces the size of exter-
nal components.
The MAX8520/MAX8521 operate from a single supply and
bias the TEC between the outputs of two synchronous
buck regulators. This operation allows for temperature
control without “dead zones” or other nonlinearities at
low current. This arrangement ensures that the control
system does not hunt when the set-point is very close
to the natural operating point, requiring a small amount
of heating or cooling. An analog control signal precisely
sets the TEC current.
Both devices feature accurate, individually-adjustable
heating current limit and cooling current limit along with
maximum TEC voltage limit to improve the reliability of
optical modules. An analog output signal monitors the
TEC current. A unique ripple cancellation scheme helps
reduce noise.
The MAX8520 is available in a 5mm x 5mm thin QFN
package and its switching frequency is adjustable up
to 1MHz through an external resistor. The MAX8521 is
also available in a 5mm x 5mm thin QFN as well as
space-saving 3mm x 3mm UCSP™ and 36-bump WLP
(3mm x 3mm) packages, with a pin-selectable switch-
ing frequency of 500kHz or 1MHz.
Applications
SFF/SFP Modules
Fiber Optic Laser Modules
Fiber Optic Network Equipment
ATE
Biotech Lab Equipment
Pin Configurations appear at end of data sheet
UCSP is a trademark of Maxim Integrated Products, Inc.
Features
o Circuit Footprint 0.31in2
o Low Profile Design
o On-Chip Power MOSFETs
o High-Efficiency Switch-Mode Design
o Ripple Cancellation for Low Noise
o Direct Current Control Prevents TEC Current
Surges
o 5% Accurate Adjustable Heating/Cooling Current
Limits
o 2% Accurate TEC Voltage Limit
o No Dead Zone or Hunting at Low Output Current
o ITEC Monitors TEC Current
o 1% Accurate Voltage Reference
o Switching Frequency up to 1MHz
o Synchronization (MAX8521)
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX8520ETP -40°C to +85°C 20 Thin QFN-EP* 5mm x 5mm
MAX8521EBX
MAX8521ETP
MAX8521EWX+
-40°C to +85°C 6 x 6 UCSP 3mm x 3mm
-40°C to +85°C 20 Thin QFN-EP* 5mm x 5mm
-40°C to +85°C 36 WLP** 3mm x 3mm
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
**Four center bumps depopulated.
Typical Operating Circuit
INPUT
3V TO 5.5V
ON
OFF
TEC CURRENT
MONITOR
CURRENT-
CONTROL
SIGNAL
VDD
PVDD
FREQ
LX1
PGND1
SHDN
CS
ITEC MAX8521
CTLI OS1
COMP
REF
GND
OS2
LX2
PGND2
OUTPUT
TEC ITEC = ± 1.5A
ANALOG /DIGITAL
TEMPERATURE CONTROL
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1 page  
www.DataSheet4U.com
Smallest TEC Power Drivers for Optical
Modules
ELECTRICAL CHARACTERISTICS (continued)
(VDD = VPVDD1 = VPVDD2 = VSHDN = 5V, 1MHz mode (Note2). PGND1 = PGND2 = GND, CTLI = MAXV = MAXIP = MAXIN = REF,
TA = -40°C to +85°C, unless otherwise noted.) (Note 7)
PARAMETER
MAXV Threshold Accuracy
SYMBOL
CONDITIONS
VMAXV = VREF x 0.67, VOS1 to VOS2 = ±4V,
VDD = 5V
VMAXV = VREF x 0.33, VOS1 to VOS2 = ±2V,
VDD = 3V
MIN
-2
-3
MAX UNITS
+2 %
+3 %
MAXV, MAXI_ Input Bias Current
CTLI Gain
CTLI Input Resistance
Error-Amp Transconductance
VITEC Accuracy
IMAXV-
BIAS, VMAXV = VMAXI_ = 0.1V or 1.5V
IMAXI_-BIAS
ACTLI
RCTLI
gm
VCTLI = 0.5V to 2.5V (Note 6)
1MΩ terminated at REF
VOS1 to VCS = ±100mV
VOS1 = VDD /2
-0.1
+0.1
µA
9.5 10.5 V/V
0.5 2.0 MΩ
50 160 µS
-10 +10 %
Note 3: Enter 1MHz mode by connecting a 60kΩ resistor from FREQ to ground for the MAX8520, and connecting FREQ to VDD for
the MAX8521.
Note 4: Includes power FET leakage.
Note 5: Duty-cycle specification is guaranteed by design and not production tested.
Note 6: CTLI Gain is defined as:
( )ACTLI
=
∆
∆VCTLI
VOS1 − VCS
Note 7: Specifications to -40°C are guaranteed by design and not production tested.
Typical Operating Characteristics
(VDD = 5V, circuit of Figure 1, TA = +25°C unless otherwise noted)
90
80
70
60
50
40
30
20
10
0
0
EFFICIENCY vs. TEC CURRENT
VDD = 5V, RTEC = 2Ω
FREQ = 500kHz
FREQ = 1MHz
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
TEC CURENT (A)
EFFICIENCY vs. TEC CURRENT
VDD = 3.3V, RTEC = 1.3Ω
90
80
70 FREQ = 500kHz
60 FREQ = 1MHz
50
40
30
20
10
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
TEC CURRENT (A)
COMMON-MODE
OUTPUT VOLTAGE RIPPLE
MAX8520/21 toc03
C2 = C7 = 1µF
VOS2
20mV/div
AC-COUPLED
400ns/div
VOS1
20mV/div
AC-COUPLED
ITEC = 1A
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
Smallest TEC Power Drivers for Optical
Modules
VDD
C1
1µF
C3
1µF
C4
1µF
C6
0.1µF
49.9kΩ
100kΩ
VDD LX1
CS
PVDD1
PGND1
PVDD2
PGND2
U1
MAX8521
OS1
OS2
REF LX2
COMP
MAXIP
MAXIN
MAXV
CTLI
FREQ
ITEC
SHDN
GND
L1
4.7µF
RSENSE
0.09Ω
C5
10µF
C2
1µF
RTHER
L2
4.7µF
C8
0.1µF
C7
1µF
VDD
ON
OFF
REF
R2
0.022µF
243kΩ
10µF
U2
MAX4475
DAC
INPUTS
10kΩ
1µF
510kΩ
TO
REF
VDD
U4
MAX5144
U3A
MAX4477
100kΩ
10kΩ
U3B
MAX4477
Figure 1. MAX8521 Typical Application Circuit
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MAX8521.PDF ] | |
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